Restraint systems in vehicles typically include a seat belt system. The seat belt system restrains an occupant during a vehicle impact. The seat belt system may include a seat belt retractor that locks a webbing to restrain the occupant. The seat belt retractor may include a torsion bar that deforms during the vehicle impact to allow additional payout of the webbing. The torsion bar allows additional payout of the webbing based on the deformation characteristics of the torsion bar. The additional payout of the webbing may reduce chest compression on the occupant of the vehicle.